They look like human, talk like human. But when a rock like 30cm high in front of them, they simply can't raise their feet to cross or step on it. Actually, jumping is the only way they can cross it. My steps of my home are all 30cm high, do I have to jump evey step in order to go upstairs?
And when the rock is higher than the characters can jump up, say half a meter. They don't know how to climb up, even a rectangular one with a flat top. Really? Is this a car with a jumping button? Cos I couldn't think of anything organic move like this.